JPH0129290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in self-holding magnetic contactors.

A conventional electromagnetic contactor opens and closes an electric circuit by using the suction force of an AC electromagnet and the return force of an elastic element such as a spring, but the electric circuit is closed. In order to maintain the contact state, that is, the state in which the contacts remain in contact, an alternating current must be applied to the electromagnet. This constant AC current not only consumes electricity, but also
There are drawbacks such as sometimes generating beats and failures due to damage to the electromagnetic coil due to temperature rise.

To overcome the above disadvantages, there is a self-holding magnetic contactor that uses permanent magnets instead of electromagnets.This type requires no electricity other than instantaneous direct current, so it is energy-saving, and While this has the advantage of eliminating damage to the excitation coil and generation of beats, it also has problems such as the need for a rectifier circuit and a power supply polarity change switch because the drive power source is direct current.

In an attempt to solve these problems, the present inventor developed a self-holding electromagnetic contactor that uses permanent magnets and can be driven by alternating current (Japanese Patent Publication No. 55743/1983).

This self-holding magnetic contactor allows for alternating current use, so it does not require a rectifier circuit, power supply polarity change switch, etc. Therefore, it combines the advantages of a conventional magnetic contactor that uses only electromagnets with the use of permanent magnets. Although it has the advantages of a self-holding magnetic contactor, it uses a high coercive force as a permanent magnet in the magnetic circuit while remaining magnetized in a fixed direction (approximately saturated magnetization state). In order to suction and release the plunger, and to prevent vibrations caused by alternating current during attraction and release, the A contact, that is, the coil, is used as in the conventional magnetic contactor, as shown in the circuit of Figure 1. It is necessary to provide a contact that changes from open to closed when excited, and a B contact, that is, a contact that changes from closed to open when the coil is excited, and to link these with the movement of the plunger. A discharge occurs between the contacts and a spark is generated.

In the figure, the contact 16 is composed of a contact a that changes from a closed circuit to an open circuit when the exciting coil 7 is excited, and a contact b that changes from a closed circuit to an open circuit when the exciting coil 8 is excited. Of these, the spark at the time of release is almost negligible, but the discharge when contact b is opened at the time of closing is large, and it is particularly desirable to prevent spark generation at this time.

The present invention is an improved invention made in an attempt to solve this problem without increasing the number of parts. A movable contact for opening and closing an electric circuit including an element that springs in a direction of separation and a fixed contact disposed opposite thereto are provided, and the permanent magnet is caused to be almost completely magnetized in the excitation coil from a substantially unmagnetized state. The gist of the present invention is a self-holding electromagnetic contactor that opens and closes an electric circuit by applying alternating current of magnetic force and applying alternating current of magnetomotive force lower than the magnetomotive force.

Here, the excitation coil and the permanent magnet are arranged in series, for example, in an arrangement as shown in FIG. This means that they are arranged in the same direction. Further, the permanent magnet used in the present invention is preferably one with a low coercive force, such as an alnico cast magnet, rather than one with a high coercive force, such as a ferrite magnet or rare earth magnet.

Hereinafter, the present invention will be explained with reference to drawings listed as examples.

FIG. 2 is a schematic diagram showing an example of the mechanism of the self-holding electromagnetic contactor of the present invention, and FIG. 3 is a circuit diagram thereof.

A frame yoke 2 containing an excitation coil 8 is housed within the outer frame 1. A non-magnetic tube 5 is erected in the center of the frame yoke 2, and a permanent magnet 6 is housed in the bottom of the non-magnetic tube 5, in contact with the frame yoke 2 and whose upper and lower magnetic pole end surfaces are sandwiched between fixed cores 4, 4. , constitutes a magnetic circuit in which permanent magnets 6 are arranged in series. Second
The broken line in the figure indicates the direction of magnetization.

A plunger 3 that can be slid up and down along a non-magnetic tube 5 is inserted above the permanent magnet 6, and a movable contact 13 is inserted at the upper end of a non-magnetic support member 9 that is fixed to the top of the plunger 3. A fixed contact 14 is provided on the outer frame 1 facing the contact 13, and a spring 10 is provided between both arms 11 of the support member 9 and the outer frame 1 as a resilient element that acts in a direction to move the plunger 3 away from the permanent magnet 6. There is.

Now, assuming that the permanent magnet 6 is in an unmagnetized state, an alternating current is applied to the excitation coil 8 by closing the switch ' shown in FIG. It is attracted by the fixed core 4, and the movable contact 13 and the fixed contact 14 of the electric circuit are closed, but the permanent magnet 6 is magnetized at the same time as the above-mentioned attraction action. However, in this case, since the direction of magnetization (polarity) of the permanent magnet 6 is the same as the excitation direction of the excitation coil 8, the plunger 3 does not vibrate even if the switch ' remains in the closed state. Therefore, in the contactor of the present invention, as shown in the electrical circuit of FIG. 3, the contact b which was necessary in the circuit of FIG.
This eliminates the problem of large discharges that occur here. Furthermore, even if the switch ′ is opened, the permanent magnet 6 is self-retained by the magnetic force in the direction in which it was magnetized at the moment when the switch ′ was opened.
The contacts 13, 14 of the electrical circuit remain closed. There is almost no discharge when the switch is opened.

When the contacts 13 and 14 of the electric circuit are to be opened, when the switch 1 is closed, an instantaneous alternating current is applied to the excitation coil 8, and the contact a is opened.

In the illustrated example, a resistor R is inserted between the excitation coil and the contact point a in order to perform both attraction and release operations with one excitation coil 8. If the resistor R is not inserted, it is the same as the magnetization performed during adsorption, and the region where release is possible is only for a moment near the coercive force Hc, so it is difficult to release reliably. By inserting the resistor R, the magnetomotive force of the excitation coil 8 is lowered than the magnetomotive force at the time of attraction, and the release is ensured by making the maximum magnetomotive force below the vicinity of the coercive force Hc. This resistance R
Of course, instead of using a release coil having the maximum magnetomotive force as described above, a separate release coil may be provided.

As described above, the AC for release is applied to the excitation coil 8.
When applied to , the half cycle of alternating current in the same direction as the magnetic flux emitted by the permanent magnet 6 only moves the operating point of the permanent magnet 6 to the first quadrant and is not effective for release, but the remaining half cycle is due to the attraction of the permanent magnet 6. In order to cancel the magnetic flux emitted to the part, the attraction and attraction force by the permanent magnet 6 is reduced, and when the attraction and attraction force becomes less than the elastic force of the elastic element 10, a gap is created and the magnet operating point is lowered. This is accelerated and released, and the contacts 13 and 14 of the electric circuit are opened. The generation of sparks at contact a during this release is comparable to that of conventional electromagnetic contactors. After being released, the permanent magnet 6 is in a substantially demagnetized state, and of course there is no attraction force to self-hold against the elastic element 10, and the next attraction is to excite the permanent magnet 6 from a substantially unmagnetized state. is done.

As an example, the coercive force of the permanent magnet 6 is approximately 600 Oe.
A Fe-Cr-Co magnet with good squareness was used, and the maximum magnetomotive force of the excitation coil 8 during attraction was set to be more than three times the coercive force of the permanent magnet at a power supply voltage of 220V. Also, the voltage of the AC for release is 120V due to the resistor R.
However, his release was guaranteed. The AC used was 60 commercial cycles.

As described above, according to the present invention, it is possible to obtain a self-holding magnetic contactor that is energy efficient and free from discharge failure without complicating the structure compared to currently used electromagnetic type magnetic contactors. possible and has great industrial value.

[Brief explanation of drawings]

FIG. 1 is an operational electrical circuit diagram of an AC self-holding magnetic contactor according to the above invention. FIG. 2 is a schematic diagram showing the mechanism of an example of the AC self-holding electromagnetic contactor according to the present invention. FIG. 3 is an operational electrical circuit diagram of the electromagnetic contactor of FIG. 2. 3: Plunger, 4: Fixed core, 6: Permanent magnet, 7: Resistor, 8: Exciting coil, 10: Resilient element (spring), 13: Movable contact, 14: Fixed contact, 15: Power supply, A', B, B': Open/close switch, 16: Contact.

Claims (1)

[Claims] 1. A magnetic circuit in which an excitation coil and a permanent magnet are arranged in series, a movable contact for electrical circuit opening/closing including an element that is connected to a movable part of the magnetic circuit and springs in a direction of separation, and a fixed contact disposed opposite thereto. and applying an alternating current of a magnetomotive force to the excitation coil to substantially completely magnetize the permanent magnet from a substantially unmagnetized state, and applying an alternating current of a magnetomotive force lower than the magnetomotive force to the electric circuit. A self-holding electromagnetic contactor characterized by its ability to open and close.